Trent Hamm, a well-known personal finance blogger, says the key to making financial lessons stick is to make them tangible. But how does one make the rewards of savings tangible?

There is the time-honored method of introducing kids to the idea of savings using three jars. It is always three; they are labeled “Spending,” “Saving” and “Giving.”

It doesn’t always translate so neatly in life – or am I the only Mom to find one or more jars empty?

The habit of filching from one jar, just once, just this time – if carried into adult life – goes far toward explaining why one-third of Americans have nothing saved for retirement, according to a “Money” magazine survey (time.com/money/4258451/retirement-savings-survey/).

Another 23 percent have less than $10,000 saved, according to that survey, and psychologist Daniel Goldstein has a theory why. Speaking in a TED talk, Goldstein describes an losing battle between the present and the future – resisting doughnuts, for example.

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CaptionParent to Parent: Helpful tips on weathering a storm

Broward County's assistant director of Public Communications, Ric Barrick, and Roxanne Vargas of NBC6 discuss helpful tips every family should know before, during and after a hurricane.

Broward County's assistant director of Public Communications, Ric Barrick, and Roxanne Vargas of NBC6 discuss helpful tips every family should know before, during and after a hurricane.

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Volunteers of the Tradewinds & Atlantic Railroad keep the train tradition alive by giving rides on diesel-powered mini trains to the public in memory of Jon Hollahan.

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“Let’s face it. The present self is present. It’s in control right now. It has these strong heroic arms that can lift doughnuts into your mouth. And the future self … doesn’t even have a lawyer … to stick up for the future self.”

The marshmallow experiment shows the same reasoning applies in younger children. In this experiment, small children are told that they can have a marshmallow right now. Or they can wait for one hour and earn two marshmallows. Most of the youngsters opt for a single immediate marshmallow.

Doing so as adults will leave them broke in old age. So what is a parent to do?

Example is a powerful tool. Share with kids the reasons the family doesn’t give a car for a 16th birthday present (the money is better invested in college with a longer return), eat dinner out more often (it is cheaper and healthier to eat at home) and didn’t buy sweatshirts at Stone Mountain in Georgia (not often worn in Florida, an impulse buy, and doesn’t preserve the memory as well as a selfie).

It doesn’t hurt for kids to witness parents modeling good habits: delaying purchases, paying with cash instead of a credit card, saving for a long-term goal.

But all of that reasoning goes out the window when friends are headed to Panera or the mall, unless somehow that resolve has been internalized.

That’s where parents come in. Psychologists long have known that rewards are more effective than punishment. In an article “Rewards are Better than Punishment: Here’s Why,” British psychologist Jay Belsky has explored the idea and found that younger and older children learn differently.

While brain scans show older children respond strongly to negative feedback, younger children’s cognitive control centers in the cerebral cortex lit up more with positive feedback.

Translating that to the jar method, Hamm says, means making money lessons tangible. In our house, we did that with financial marshmallows: When Paul went to the grocery store with enough money for chicken broth, and came home with savings because he compared prices and bought generic instead of brand-name, I let him keep the money.

Likewise, when Sarah and Paul went to camp with spending money and a week with nothing to spend it on but cookies, candy and sundries at the canteen, Paul came home with nothing but wrappers. Sarah came home with all but $1. I let her keep the balance.